Helena Velichová

Monitoring of biogenic amines in cheeses manufactured at small-scale farms and in fermented dairy products in the Czech Republic

The aim of the study was the monitoring of six biogenic amines (histamine, tyramine, phenylethylamine, tryptamine, putrescine, and cadaverine) and two polyamines (spermidine and spermine) in 112 samples of dairy products purchased in the Czech Republic, namely in 55 cheeses made in small-scale farms and in 57 fermented dairy products. The products were tested at the end of their shelf-life period. Neither tryptamine nor phenylethylamine was detected in the monitored samples; histamine was found only in four cheese samples containing up to 25mg/kg. The contents of spermine and spermidine were low and did not exceed the values of 35 mg/kg. Significant amounts of tyramine, putrescine, and cadaverine occurred especially in cheeses produced from ewes milk or in long-term ripened cheeses. In about 10% of the tested cheeses, the total concentration of all the monitored biogenic amines and polyamines exceeded the level of 200mg/kg, which can be considered toxicologically significant. In fermented dairy products, the tested biogenic amines occurred in relatively low amounts (generally up to 30 mg/kg) that are regarded safe for the consumers health.

Interaction of polyphenols and wine antioxidants with its sulfur dioxide preservative

Wine is considered to be a significant alcoholic beverage, which is the result of fermentation of grape must or mash. Wine is a must when the substances contained in it play a major role, which are essential inhibiting water, carbohydrates, acids, minerals, nitrates, polyphenols and aromatics. These biochemical components are an important tracking element in wine evaluation in terms of chemical analyzes. An important parameter of monitoring is polyphenolic substances. Polyphenol substances are identified in plant materials as several thousand pieces with a very diverse structure. However, they have a common feature up to one or more aromatic rings substituted with hydroxyl groups. These substances may be present in plant material in a small or large amount. The total daily intake of polyphenols is estimated at 1 g. This is a higher intake than antioxidant vitamin intakes and it is confirmed that their antioxidant activity is higher than that of antioxidant vitamins. When monitoring the content of all polyphenols (TPC) in selected samples using a spectrophotometric method, a higher TPC content of red wines against white white wines can be observed. Total antioxidant activity is introduced to compare antioxidant effects of different mixtures and is based on the ability to eliminate radicals. Antioxidant activity and effects of polyphenols can be inhibited by the addition of preservatives to wine. The preservative is sulfur dioxide (SO2), which has antimicrobial and antioxidant effects. This compound is not harmless because it is a strong allergen, blocks bacteria in the digestive tract and prevents the conversion of sugars and alcohol derivatives in the liver by blocking vitamin B. In the normal life, SO2 is consumed under the E 220 mark. The aim of this work is to monitor the change in the total polyphenols content related to free and bound sulfur dioxide (SO2) content using accredited OIV-MA-AS323-O4B: R, 2009 samples in wine samples. Comparison of organic wines and wines produced by classical, it was found that organic wine have a higher content of biologically active substances and have a strong correlation factor TAA total SO2 (r = 0.77 to 0.91), depending on the wine variety.

Is air-drying of plant-based food at low temperature really favorable? A meta-analytical approach to ascorbic acid, total phenolic and total flavonoid contents

ABSTRACT The aim of this work was to review the studies that evaluated the effect of drying temperature on the content of ascorbic acid (AA), total phenolic (TPC), and total flavonoid contents (TFC) in fruits and vegetables, and quantify whether drying at 40 °C is more favorable than at higher temperatures. For the purpose of this study, AA, TPC, and TFC values for 40 °C were compared with those obtained at 50 °C, 60 °C, and 70–80 °C. A meta-analysis was performed using the weighted response ratio calculated for each experiment. Despite the fact that other variables significantly influenced the nutrient content in individual experiments, the meta-analysis provided a general view on the effect of air-drying temperature on the quality of plant-based food products from outcomes of various studies.

Addition of rutin/quercetin mixture to spreadable processed cheese: antioxidant and textural characteristics

Spreadable processed cheese is a traditional product made from a mixture of cheese, fat, water and emulsifying salts.The aim of this research was prepared spreadable processed cheese with new functional properties. Spreadable processed cheese enriched with the mixture (1:1) of rutin and quercetin (1.0 g.100g -1 ) was prepared at two melting temperature (80°C and 90°C) for three holding times (1, 5 and 10 min). The effect of melting temperature and holding time on the quercetin and rutin content was assessed using liquid chromatography with UV detection after ultrasonic-assissted extraction to methanol. The corresponding antioxidant characteristics were determined using spectrophotometric assays for total phenolics (TPC) and radical scavenging activities DPPH and ABTS. The extraction yield for quercetin varied from 45.8 to 66.4% and from 12.8 to 40.8% for rutin. The level of quercetin significantly descrased with the increase of holding time, while rutin content has increased with the increase of melting temperature. TPC values ranged from 10.8. to 14.8 mg GAE·g -1 in SPC sample enriched with rutin/quercetin mixture, and the increase of melting temperature resulted in the decrease of TPC values. DPPH and ABTS assays did not reveal any statistically significant pattern using Kruskal-Wallis ANOVA. The addition of the mixture of flavonoids into the processed cheese significantly reduced the complex modulus in comparison with the control sample (without flavonoids). This indicate that the structure of enriched SPC sample was more flexible than those in control processed cheese samples. Both melting temperature and holding time increased the complex modulus. Spreadable processed cheese are scarcely used as a carrier of flavonoids in scientific researches probably due to very complex matrices. Our research proved that spreadable processed cheese containing rutin/quercetin mixture can be used as a functional food.